Randomized Trial of Intravitreal Clindamycin and Dexamethasone Versus Pyrimethamine, Sulfadiazine, and Prednisolone in Treatment of Ocular Toxoplasmosis

Purpose: To compare the efficacy of intravitreal injection of clindamycin and dexamethasone with classic treatment for ocular toxoplasmosis.

Design: Prospective, randomized single-masked clinical trial.

Participants: A total of 68 patients with active ocular toxoplasmosis were assigned randomly to 2 treatment groups: 34 in the intravitreal clindamycin plus dexamethasone (IVCD) group and 34 in the classic treatment (CT) group.

Intervention: The IVCD group received 1 to 3 injection(s) of 1 mg intravitreal clindamycin and 400 μg dexamethasone, and the CT group received 6 weeks of treatment with pyrimethamine and sulfadiazine plus prednisolone. Antitoxoplasmosis antibodies (immunoglobulin [Ig] M and IgG) were measured using an enzyme-linked immunosorbent assay.

Main Outcome Measures: Changes in retinochoroidal lesion size, measured by a computer program written in the MATLAB environment, 6 weeks after initiation of treatment. Visual acuity (VA) changes, vitreous inflammatory response, adverse drug reactions, and rate of recurrence were secondary outcome measures.

Results: The mean number of injections in the IVCD group was 1.6. The lesion size reduction was statistically significant after treatment in both IVCD and CT groups (P < 0.001 and P = 0.009, respectively). However, the difference in mean percentage of reduction at 6 weeks was not significant: 57.0 ± 27.8% in the IVCD group versus 58.4 ± 29.3% in the CT group (P = 0.569). In relation to the baseline, VA increased by 0.44 ± 0.24 and 0.29 ± 0.19 logarithm of the minimum angle of resolution units in the IVCD and CT groups, respectively (P < 0.001); however, the difference of VA improvement between the groups was not significant. The interaction effect of IgM and treatment group on lesion size reduction was significant (P = 0.002); this indicated that IgM-positive cases responded better to CT and IgM-negative cases responded better to IVCD treatment. Vitreous inflammation reduction was insignificant between the groups. Within 2 years, 4 eyes (2 in each group) had 1 episode of recurrence. Adverse drug reactions occurred in 2 patients in the CT group. No major injection-related complication was encountered in the IVCD group.

Conclusions: Intravitreal injection of clindamycin and dexamethasone may be an acceptable alternative to the classic treatment in ocular toxoplasmosis. It may offer the patient more convenience, a safer systemic side effect profile, greater availability, and fewer follow-up visits and hematologic evaluations.